GitHub User: Daxter
That totally exists now. They're called Batch Actions :]
Kind of. It will sort by the ids of the parent model, instead of something more useful (like alphabetical sorting).
Perhaps because you're not using the add function? The below format works fine for me.
errors.add(:name, 'Try again!') unless is_cool?(name)
The command rails g active_admin:resource product doesn't actually create a model; it just creates the app/admin/products.rb file so Active Admin renders a GUI for this resource when you start your server. You've got to run rails g model product first.
rails g active_admin:resource product
rails g model product
Assigning before_create (etc) callbacks in your model work just fine with ActiveAdmin. What exactly is your problem?